1. Field of the Disclosure
The present disclosure relates to balancing a rotating part, such as a rotating part of a gas turbine engine. Aspects of the present disclosure relate to a balancing kit, a balancing mass, a balancing receptacle, and a balancing method.
2. Description of the Related Art
The rotor discs of compressors and turbines of gas turbine engines rotate at very high speed in use. It is important for the rotating components, including the discs, to be properly balanced, because any imbalance may result in unwanted movement of the rotating components, for example due to bending of a shaft about which the rotating components rotate. This may result in unwanted contact between rotating and stationary parts and/or an increase in the required tolerance gap between rotating and stationary parts, such as between rotating blades and surrounding cases. In turn, this may result in efficiency losses and/or vibrations, which may lead to damage, for example to bearings.
Accordingly, rotating discs of gas turbine engines need to be precisely balanced during manufacture and assembly. The discs may be balanced firstly during manufacture of the discs themselves, for example by removing material in a conventional manner. The discs may then be precision balanced again after assembly with other rotating components, such as blades that are attached to the disc. It may also be necessary to re-balance rotating components, such as discs, during service of the engine.
One method for precision balancing rotors involves providing grub screws to a rotor disc at various positions around its circumference. The grub screws may be screwed into corresponding threads in the disc. In this way, the rotor can be balanced by selecting the appropriate position and/or number of grub screws around the disc.
As mentioned above, a disc may need to be re-balanced through its service life, for example due to wear. However, where grub screws are used to balance a disc, the screws may seize in their threads during operation. This may be due to the extreme operating environment, including very high temperatures. This means that rebalancing of a disc may be extremely difficult, particularly rebalancing of a disc in-situ. The problem is exacerbated because the grub screws need to be particularly tight during operation of the engine to ensure that they do not become loose, because if a screw were to come free during operation it could cause significant damage to the engine. Thus, the grub screws need to be tight, but this increases the possibility of the seizing.